News Release

CAMBRIDGE, Mass.--(BUSINESS WIRE)--Nov. 9, 2017--
Ra
Pharmaceuticals, Inc. (NASDAQ:RARX), a clinical stage
biopharmaceutical company focusing on the development of next-generation
therapeutics for the treatment of complement-mediated diseases, today
announced financial results for the third quarter ended September 30,
2017, and provided an update on recent corporate and clinical
developments, including enrollment in the Phase 2 program for RA101495
SC in paroxysmal nocturnal hemoglobinuria (PNH) and progress toward the
initiation of a Phase 2 study in generalized myasthenia gravis (gMG).

“Enthusiasm for a convenient, subcutaneous (SC), self-administered C5
inhibitor continues to be reflected in the rapid recruitment of our
Phase 2 PNH study, with 28 patients enrolled to date,” said Doug Treco,
PhD, President and Chief Executive Officer of Ra Pharma. “We look
forward to reporting data from this program around the end of the year,
initiating our Phase 2 study in gMG, and expanding our RA101495 SC
clinical program by initiating a Phase 1b renal impairment study to
support clinical trials in atypical hemolytic uremic syndrome and lupus
nephritis. We believe RA101495 SC holds the potential to become an
important and convenient treatment option accessible to a broad spectrum
of patients across a number of complement-mediated diseases.”

Recent Developments

Progressed enrollment in Phase 2 clinical program evaluating RA101495
SC in PNH, with 28 patients enrolled to date. A total of 27 patients
have been dosed with RA101495 SC, including 10 patients in Cohort A
(eculizumab-naïve patients), 16 patients in Cohort B (patients
switching from eculizumab to RA101495 SC), and one patient in the
third cohort (inadequate responders to eculizumab). The Company
remains on track to report additional data around the end of the year.

Opened an Investigational New Drug (IND) application with the US Food
and Drug Administration and activated sites in preparation for the
Company’s Phase 2 trial evaluating RA101495 SC for the treatment of
gMG. gMG is a complement-mediated autoimmune disease that causes
muscle weakness and reduced mobility. Convenient, self-administered
RA101495 SC has the potential to address a broader gMG patient
population than is practical with intravenous infusions. This target
population includes, but is not limited to, patients who have failed
multiple immunosuppressants. Ra Pharma anticipates dosing the first
patient in this Phase 2 trial in the fourth quarter of this year.

For the third quarter of 2017, the Company reported a net loss of $15.3
million, or a net loss of $0.68 per share (basic and diluted), compared
to a net loss of $8.1 million, or a net loss of $14.22 per share for the
same period in 2016.

Research and development expenses for the third quarter of 2017 were
$13.1 million, compared to $7.1 million for the same period in 2016. The
increase in R&D expenses for the third quarter 2017 was primarily due to
clinical development costs associated with our lead program, RA101495
SC, for the treatment of PNH.

General and administrative expenses for the third quarter of 2017 were
$2.3 million, compared to $1.0 million for the same period in 2016. The
increase in G&A expenses for the third quarter 2017 was due primarily to
employee-related costs, including salary, benefits, and non-cash
stock-based compensation due to the increase in G&A headcount to support
the growth of the Company.

There was no revenue earned in the three months ended September 30, 2017
or the three months ended September 30, 2016.

As of September 30, 2017, Ra Pharma reported total cash and equivalents
of $84.1 million. The Company expects that its cash and cash equivalents
will be sufficient to fund operations through the end of 2018.

Ra Pharma is developing RA101495 SC for paroxysmal
nocturnal hemoglobinuria (PNH), generalized
myasthenia gravis (gMG), atypical hemolytic uremic syndrome (aHUS),
and lupus
nephritis (LN). The product is designed for convenient, once daily
subcutaneous (SC) self-administration. RA101495 SC is a synthetic,
macrocyclic peptide discovered using Ra Pharma’s powerful proprietary
drug discovery technology. The peptide binds complement component 5 (C5)
with sub-nanomolar affinity and allosterically inhibits its cleavage
into C5a and C5b upon activation of the classical, alternative, or
lectin pathways. By binding to a region of C5 corresponding to C5b,
RA101495 SC also disrupts the interaction between C5b and C6 and
prevents assembly of the membrane attack complex (MAC). This activity
defines an additional, novel mechanism for the inhibition of C5
function. In Phase 1 studies in healthy volunteers and as noted in the
initial data reported in June 2017 on two eculizumab-naïve patients in
Ra Pharma’s Phase 2 program, dosing of RA101495 SC was well tolerated
and demonstrated sustained and near complete suppression of hemolysis
and complement activity. To learn more about RA101495 SC, please visit: http://rapharma.com/pipeline/ra101495/.

About RA101495 SC Phase 2 PNH Clinical Program

The global, dose-finding Phase 2 program is designed to evaluate the
safety, tolerability, preliminary efficacy, pharmacokinetics, and
pharmacodynamics of RA101495 SC in patients with PNH. The study will
evaluate RA101495 SC in three cohorts. Cohort A includes
eculizumab-naïve patients, Cohort B includes patients switching from
eculizumab to RA101495 SC, and a third cohort includes patients who are
currently treated with eculizumab, but have evidence of an inadequate
response. Patients in all three cohorts will be eligible for a long-term
extension study following the completion of the initial 12-week studies.
The primary efficacy endpoint is change in lactate dehydrogenase (LDH)
from baseline to the mean level from week 6 to week 12.

About RA101495 SC Phase 2 gMG Clinical Program

The Phase 2, multicenter, randomized, double-blind, placebo-controlled
trial is designed to evaluate the safety, tolerability, and preliminary
efficacy of RA101495 SC in patients with gMG. The trial will enroll
approximately 36 patients and will include a screening period of up to
four weeks. At the outset of the 12-week treatment period, patients will
be randomized in a 1:1:1 ratio and will receive daily, subcutaneous
doses of 0.1 mg/kg of RA101495 SC, 0.3 mg/kg of RA101495 SC, or matching
placebo. The primary efficacy endpoint is change in Quantitative
Myasthenia Gravis (QMG) score from baseline to week 12. All patients
will have the opportunity to receive RA101495 SC in a long-term
extension study.

About Ra Pharmaceuticals

Ra Pharmaceuticals is a clinical stage biopharmaceutical company
focusing on the development of next-generation therapeutics for
complement-mediated diseases. The Company discovers and develops
peptides and small molecules to target key components of the complement
cascade. For more information, please visit: www.rapharma.com.

Forward-Looking Statement

This press release contains "forward-looking statements" within the
meaning of the Private Securities Litigation Reform Act of 1995,
including, but not limited to, statements regarding the safety, efficacy
and regulatory and clinical progress of our product candidates,
including RA101495 SC, including the timing, designs, plans and
announcement of results regarding our ongoing and future studies and
programs described in this press release, and our expected cash runway
from existing cash and cash equivalents. All such forward-looking
statements are based on management's current expectations of future
events and are subject to a number of risks and uncertainties that could
cause actual results to differ materially and adversely from those set
forth in or implied by such forward-looking statements. These risks and
uncertainties include the risks that Ra Pharma’s product candidates,
including RA101495, will not successfully be developed or
commercialized; the risk that initial data from the Company’s global
Phase 2 clinical program evaluating RA101495 for the treatment of PNH
may not be indicative of final study results; the risk that initial data
from a limited number of patients may not be indicative of results from
the fully patient enrollment planned for such study; as well as the
other factors discussed in the “Risk Factors” section in Ra Pharma’s
most recently filed Annual Report on Form 10-K, as well as other risks
detailed in Ra Pharma’s subsequent filings with the Securities and
Exchange Commission. There can be no assurance that the actual results
or developments anticipated by Ra Pharma will be realized or, even if
substantially realized, that they will have the expected consequences
to, or effects on, Ra Pharma. All information in this press release is
as of the date of the release, and Ra Pharma undertakes no duty to
update this information unless required by law.

Ra Pharmaceuticals, Inc.

Condensed Consolidated Balance Sheets

(Unaudited)

(In thousands)

September 30, 2017

December 31, 2016

Assets

Cash and cash equivalents

$

84,091

$

117,812

Prepaid expenses and other current assets

1,123

1,690

Property and equipment, net

5,967

5,537

Other noncurrent assets

1,730

1,779

Total assets

$

92,911

$

126,818

Liabilities and Stockholders’ Equity

Accounts payable and accrued expenses

$

7,371

$

6,434

Deferred rent

432

303

Noncurrent liabilities

2,531

2,859

Stockholders' equity

82,577

117,222

Total liabilities and stockholders’ equity

$

92,911

$

126,818

Ra Pharmaceuticals, Inc.

Condensed Consolidated Statements of Operations

(Unaudited)

(in thousands, except per share data)

Three Months EndedSeptember 30

Nine Months EndedSeptember 30

2017

2016

2017

2016

Revenue

$

-

$

-

$

-

$

4,928

Operating expenses:

Research and development

13,130

7,079

32,606

18,541

General and administrative

2,284

1,042

7,101

3,418

Total operating expenses

15,414

8,121

39,707

21,959

Loss from operations

(15,414

)

(8,121

)

(39,707

)

(17,031

)

Other income (expense), net

139

7

409

(945

)

Net loss

$

(15,275

)

$

(8,114

)

$

(39,298

)

$

(17,976

)

Net loss per common share – basic and diluted

$

(0.68

)

$

(14.22

)

$

(1.74

)

$

(32.73

)

Weighted average number of common shares outstanding – basic and
diluted